If ICs are plugged between ZMA and Oppo, I get buzz, even if the Oppo is *not* plugged into the P10

I've eliminated as much as I can - this narrows it down to the Oppo and ZMA - with and without the P10.

LR: Do you have an old CD Player or Bluray Player you can hook up in place of the Oppo for test purposes. Seems like if the Oppo and say a CD player were to cause the same Buzz then we are back to the ZMA?

I would expect the chassis of your P10 to be connected to Earth Ground at you power outlet. You might check for any voltage reading between the ZMA chassis and the chassis of your P10. There should not be any if the ZMA chassis is grounded to the P10 via the ZMA power cord as we would expect.

If you do get a voltage reading between the two then try attaching a simple test lead with alligator clips on each end. One clip on a chassis screw at the ZMA and one clip on a chassis screw at the P10 (this simply acts as an alternate path to earth ground). Over the years in sorting out ground loops I have had voltage readings between components of as much as 2.00 volts and as little as 0.02 volts cause AC Hum.

Also check for any voltage differential between ZMA and the Oppo. Also try attaching a test lead between Oppo chassis and ZMA chassis as well as Oppo chassis to P10 chassis. If we have Voltage in a chassis then we want to provide an alternate path to earth ground other that the interconnects.

If you have nothing connected to the Oppo, power plug is unplugged, no input connections from other source devices (cable box etc.) and you attach interconnects between the 2-channel audio output from the Oppo to the 2-channel audio input on your ZMA and you have a Buzz???

Then I would have to think somehow there is a loop Out through one of the ZMA audio inputs through the Oppo and back into the other ZMA audio input?

LR: Do you have an old CD Player or Bluray Player you can hook up in place of the Oppo for test purposes. Seems like if the Oppo and say a CD player were to cause the same Buzz then we are back to the ZMA?

Yeah, that was my next test. I have an old copper chassis Denon I picked up in my early days with the 2 watt Zen Amp, it's been relegated to garage duty - damn thing weighs in at 30# or so so it doesn't get moved often. I'm going to drag that up next and see what happens.

Quote:

If you have nothing connected to the Oppo, power plug is unplugged, no input connections from other source devices (cable box etc.) and you attach interconnects between the 2-channel audio output from the Oppo to the 2-channel audio input on your ZMA and you have a Buzz???

Then I would have to think somehow there is a loop Out through one of the ZMA audio inputs through the Oppo and back into the other ZMA audio input?

My thoughts exactly, that would make me think there is a fault in one of the two devices - or possibly my interconnects.

This is my problem too, AS YOU GUYS (DBC & LR) HAVE STATED**. I put my SE84CS back in.....and wah la!........no ground loop. So, have you tried just putting your C+ back in as the only variable change LR?

Anyway, it's not IC's or Speaker cable picking it up by evidence of the SE84CS being fine.

The good news is...Steve will make it right. Possibly the first or secondary winding of the Tranny's OR AC leakage....DC issue in the ZMA. Will get to see the solution LR, with your ZMA and with your close proximity a couple times a week from work = quick turnaround...and then I'll get mine on the road back to Decware!

Obviously, the ground loop caused by the ZMA is unacceptable and dangerous to our Speaker's and Equipment....plain annoying too!So, in regards to my reply #88...mine is a little more than just a hum=ground loop...and my evidence (once again), of the SE84CS being clean = ZMA is the culprit.

Furthermore, I see Lonely Raven and I as Beta Tester's....which is just fine. Also, if you go to the Mystery Amp Thread, ...go back a few pages...I am currently running a 7 amp fuse instead of a 5 amp fuse. My ZMA would blow the 5 & 6 amp fuses consistently. However, with the first time initial start up/turn on, it ran for 12.5 hours off the 5 amp fuse that came in it.

Maybe I have an issue from shipping damage, for both the fuse issue and the ground loop issue...I have. The fuse could be due to the cold in shipping and I need to try backing the ZMA down from a 6 amp fuse first, then to 5 amp fuse.

HAVING SAID THIS: I am committed to this AMP/ZMA...now at 105 hours...even with an issue(s) I/we/Decware will find a solution to...the FIDELITY OF THIS AMP IS ENGROSSING TO SAY THE LEAST. I MIGHT DRIVE IT TO PEORIA MYSELF...SO IT DOES NOT LEAVE MY SIGHT. Hyperbole, not at all....it is that good. I have auditioned and have had some of the best Tube & Solid State through my Listening Room (and recently-I must add)....I want my ZMA!

YOU GUYS STATED**:"If you have nothing connected to the Oppo, power plug is unplugged, no input connections from other source devices (cable box etc.) and you attach interconnects between the 2-channel audio output from the Oppo to the 2-channel audio input on your ZMA and you have a Buzz???

Then I would have to think somehow there is a loop Out through one of the ZMA audio inputs through the Oppo and back into the other ZMA audio input?

My thoughts exactly, that would make me think there is a fault in one of the two devices - or possibly my interconnects".

LR wrote: I knew most of that already and have already worked out most of those possible issues (except I've not measured the differences between circuits).

LR: Check for any Voltage potential between Earth Grounds while the system is powered up and current is flowing.

In my case I use 3 separate wall outlets. My Oppo and Super Zen are connected to a Tripp Lite isolation transformer that is plugged into the first wall outlet. My Left Sub and Mid Bass Module are plugged into a Monster Surge Protector / Isolator that is plugged into the second wall outlet. My Right Sub and Mid Bass Module are plugged into a Monster Surge Protector / Isolator that is plugged into the third wall outlet.

My Monster Surge Protectors and Tripp Lite isolation transformer all have metal chassis that are connected directly to Earth Ground via their respective 3-prong power cords. So in my case with the system powered up I simply check for Voltage potential between any of the 3 power source device chassis.

If you find any voltage potential between power source devices then most times just connecting all three chassis together using alligator clip test leads provides everything access to the Earth Ground with lowest potential to ground.

So instead of current trying to get to the Earth Ground of lowest potential through your audio cables it now has an alternate path via the power cord of each audio component to the power source device it is connected to and to the Earth Ground of lowest potential via the test leads connecting the chassis of all 3 power source devices.

Having said all that you may not have an Earth Ground or Ground Loop Issue. But going through the process will rule that out for sure.

Did you have the chance to get your Denon CD Player in or your Zen modded Amp (C+...I think you said it is)?

I have narrowed it down to the ZMA, as I stated above. Pretty darn sure anyway. -S

No, after my 3 hour drive home from work last night, I listened to some DSD files quietly for an hour, then went to bed.

I hope to make time for some testing tonight. I've already done what Steve suggested in the ZMA thread - I'm going to repeat all my tests as best as I can, starting from the speaker back as Steve suggested (which I've already done) and see what happens.

I hate to have to say this, but there are no issues with the ZMA, and no differences between the ZMA or any of our amplifiers with respect to ground loops. The earth ground at the IEC connector is bonded to the metal chassis and the audio ground of the amplifier is also connected to earth ground. This can be verified by taking an ohm meter and testing between the ground lug of the IEC connector and the metal chassis and then again from the earth ground at the IEC connector to the outside part of any RCA jack. And finally, from the outside part of the RCA jack to the metal chassis. All three points will read as far below 1 ohm as your meter's cables are capable of reading (usually 0.4 ohms +/- 0.3 ohms)

DBC's suggested tests are recommended.

Another comment I'd like to make is that hum or noise from an amplifier has nothing to do with clean or dirty power. The two are completely separated from each other.

Dirty power causes the sound to become dry, grainy, less dimensional, somewhat flat, but it does not cause noise or hum issues unless there is a problem with house wiring, such as a bad neutral or ground rod.

The first ZMA enjoyed months in my private system with zero noise, followed by a week of continued use during Decfest with a variety of sources and speakers with zero noise and 85 witnesses. The second ZMA also was (and I'm sure is) noise free. The way to find out is very simple... just unplug your source components and remove all interconnects from the ZMA and turn it on. If there isn't any noise, then you know it's not the amp itself causing your grief.

I haven't been following this lengthy thread so I've only read the last few posts, but it seems both ZMA's are being used with OPPO which is connected to a TV via HDMI. If the TV is connected to cable there are certainly some opportunities for ground loops. Make sure if a cable is connected to your TV or TV box, that you are using a 75 ohm isolation transformer on the incoming cable itself to decouple the grounds from your TV and the Cable coming into the house.

And I realize people probably don't want to call me unless they have no other choice, but today is the first I knew of the buzz issues you guys are having.

I've just spent two wonderful nights with the next ZMA and it too has no noise issues and is in the shipping department with my full faith that it has no design issues or noise problems whatsoever.

Dirty power causes the sound to become dry, grainy, less dimensional, somewhat flat, but it does not cause noise or hum issues unless there is a problem with house wiring, such as a bad neutral or ground rod.

I was exhausted from work, but still spent a couple hours on this last night. Looks like I was right about there being two different buzzes going on, which is what was making this so difficult to suss out.

I repeated all the tests I did before, which was the same thing Steve suggested; starting from the speakers back.

The buzz goes up and down with the volume knob. The ZMA itself is dead quiet - everything starts when connecting outside devices.

Buzz #1, Interconnects acting like antenna - this was the buzz I was getting even with the Oppo unplugged. Since I rearrange my system over the weekend, this buzz has been minimized. It's still there, but I refuse to go to shielded ICs because they sound flatter, like they lose some air. (at least with the ones I have available to me)

Buzz #2, The Oppo. *nothing* plugged into the Oppo except ICs - I get a little of the antenna buzz mentioned above - as soon as I plug in power, I get a heavier buzz that's clearly apparent from the seating position. Again, *nothing* plugged into the Oppo except the ZMA.

If I plug in my old Denon CD player, I only get Buzz #1. It sounds really good on the ZMA by the way, softer and more forgiving than the Oppo.

If I plug my SE84A Zen Amp in place of the ZMA, connected to Oppo or Denon, I only get Buzz #1

I tried plugging both the ZMA and Oppo directly into the same wall outlet - Same buzz issue, with the added bonus of gaining transformer buzz. Tried both devices connected to my Trip Lite isolation transformer, and I was rewarded with the Trip Lite having some nasty transformer buzz, plus the #1 and #2 buzz above.

Again, as I've said before, the ZMA is dead quiet on it's own. The only thing I can figure is that the Oppo has an issue, or is causing an issue when mixed with the ZMA - I'm sort of at a loss for what to do now. Sending Oppo another E-mail to see what they suggest.

Well, I really want this resolved - I wish I better understood what was going on (electrically) that was causing the buzz. Plus, Steve seemed pretty miffed above. LOL So I wanted to do my due diligence.

On the plus side, this has basically proven that the P10 does what they say it does. The balanced power did get rid of the transformer buzz I had with the little Zen amp, the transformers run cooler, and it's really starting to sharpen the music up.

If I can just resolve this last buzz issue I think I'd be *very* happy with the system.

I have an Audio Play Date (as Brianne calls it) with Palomino this weekend. I'm going to bring my gear over to his audio temple and see if we can replicate the issues; plus I'm wanting to put my Oppo up against his little DAC and see what's what. It should be a very revealing event.

LR Wrote: I wish I better understood what was going on (electrically) that was causing the buzz.

LR, just because you have not solved the problem this does not mean you are not making progress. If you want to quantify what's going on you are going to have to get your hands on a decent Digital Volt Meter and Test Leads with alligator clips on on each end. Both can be had for not a lot at Radio Shack.

"Buzz #2" definitely sounds like AC Current flowing between the ZMA and Oppo via the interconnects when the ZMA & Oppo are plugged in. Remove the interconnects between the two devices and power both devices up. Using your Digital Volt Meter set at say a range of 20 Volts AC touch one meter lead to the ZMA chassis and the other to the Oppo Chassis. If you read a voltage then you have a voltage potential between the two. Now to solve that problem.

Try attaching one end of a test lead to the Oppo chassis and the other end to the ZMA chassis (typically I attach the alligator clips to an unpainted chassis screw). Now check for any Voltage potential between the two devices again with your Digital Volt Meter. There should not be any voltage differential since the test lead between the two device chassis will in effect tie the earth grounds of each together. If this is the case then try installing the interconnects to see if Buzz #2 still exists.

If you do this and report back your finding then I can help you with the next steps.